Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for the characterization of proteins both by introduction of a spin label probe and by characterization of metal binding sites. Although the NIH supported researchers at UCLA who utilize this technique are spread out in several different departments, there is a long history of sharing of the available equipment as evidenced by many joint publications resulting from these fruitful collaborations. A Center for Biological EPR has been recently established to improve the visibility of the available EPR resources for the benefit of other potential users. At this time, there is a critical need to upgrade much of the very old EPR instrumentation that has supported research in this area for many years. The research projects of three NIH supported major users are described with the following titles: l) Structure and Dynamics of Proteins Using Site-Directed Spin Labeling; 2) Structure-Function Studies on the Lactose Permease of Escherichia coli using Electron Paramagnetic resonance; and 3) Electron Paramagnetic Resonance (EPR) Studies on the Structure and Function of FALS-Mutant Proteins of Copper-Zinc Superoxide Dismutase. Five additional NIH supported researchers are potential users of the requested instrumentation.